In recent years, near-field wireless communication schemes utilized within a room such as an office or a household have come to prominence, with services and products using wireless communication schemes such as those conforming to IEEE802.11b and IEEE802.11g (for example, backward compatible with b) that are wireless LAN (Local Area Network) standards and the Bluetooth (registered trademark) standard targeting connection between various equipment such as computers and mobile terminal stations etc. already having been implemented. Such wireless communication schemes can eliminate the inconvenience of cable wiring because connection between equipments are established wirelessly, but communication is difficult in equipments conforming to different standards due to different communication schemes including, for example, a modulation method, codec, and protocol. Further, the communication standards IEEE802.11b, and Bluetooth (registered trademark) share a single frequency band of 2.4 GHz referred to as ISM (Industrial Scientific and Medical) and can be introduced in a straightforward manner to carry out wireless communication without need of a license, but, conversely, there is the possibility of mutual interference occurring when used in close proximity.
As one of a method of resolving problems such as poor interconnectivity due to differences in wireless communication standards and mutual interference within the same frequency band, a method of selectively switching between communication schemes in use according to wireless transmission path conditions after making a configuration of a wireless station a so-called multimode configuration that is compatible with a plurality of wireless communication schemes has been considered (for example, refer to patent document 1). As a result, even if wireless transmission path conditions change, it is possible to carry out efficient wireless communication in accordance with this change.
An example of a communication control method using a multimode configuration of the related art will be described using FIG. 37. FIG. 37 shows an example of installation conditions of apparatuses within wireless communication area AR1 of close proximity using a 2.4 GHz band.
Communication is carried out using a wireless communication scheme conforming to the Bluetooth (registered trademark) standard or the IEEE802.11b standard between multimode control station 10 and a plurality of terminal stations. Here, multimode terminal stations 20-1 and 20-2, Bluetooth (registered trademark)-compatible terminal station 20-3, and IEEE802.11b-compatible terminal station 20-4 are shown as an example of a plurality of terminal stations existing within wireless communication area AR1. Wireless communication is then carried out while performing switching control every time between multimode control station 10 and multimode terminal stations 20-1 and 20-2 so as to ensure that communication functions at each wireless station are compatible with one communication scheme. Further, when wireless communication is carried out between multimode control station 10 and Bluetooth (registered trademark)-compatible terminal station 20-3 or IEEE802.11b-compatible terminal station, the communication is performed such that multimode control station 10 is controlled to switch to a wireless function that is compatible with terminal station 20-3 or terminal station 20-4.
Other scheme-compatible wireless stations 30-1 and 30-2 are installed within the same wireless communication area AR1, and carry out wireless communication using a separate communication link in the same ISM band. Here, a low power communication link for a local telephone is given as an example of a separate communication link. A frequency band that overlaps partially or completely with the frequency band used in the communication links between the multimode control station 10 or multimode terminal station 20-1 and IEEE802.11b-compatible terminal station 20-4 during calls is taken to be used for this communication link. Further, a microwave oven 40 taken as apparatus using electromagnetic waves of the same 2.4 GHz band is also provided within the area AR1. Let the case be assumed where at least one of other scheme-compatible wireless stations 30-1 and 30-2 and microwave oven 40 are set close to multimode control station 10 in terms of a positional relation.
Within the wireless communication area AR1 of the installation conditions described above, when there is a need of data transmission with terminal stations 20-1 to 20-4, multimode control station 10 carries out wireless communication using a compatible communication schemes every time in the ISM waveband. Control of wireless communication at multimode control station 10 is then carried out by control section 11. When carrying out communication with Bluetooth (registered trademark)-compatible terminal station 20-3, communication is carried out by switching the wireless communication function to Bluetooth (registered trademark)-compatible processing section 12. Also, when carrying out communication with IEEE802.11b-compatible terminal station 20-4, communication is carried out by switching the wireless communication function to an IEEE802.11b compatible wireless processing section 13. As a result of using this configuration and communication control, it is possible for multimode control station 10 to carry out communication with terminal stations 20-3 and 20-4 compatible only with the respective Bluetooth (registered trademark) and IEEE802.11b standards, and increase connectivity between equipments compatible with different communication standards.
On the other hand, it is possible to carry out wireless communication control as shown below between multimode control station 10 and multimode terminal station 20-1. First, switching control is carried out so as to carry out wireless communication using IEEE802.11b-compatible wireless processing section 13. After a wireless communication scheme conforming to the IEEE802.11b standard is carried out, namely, after baseband signal processing such as predetermined frame configuration and predetermined modulation processing is carried out, predetermined analog wireless processing such as frequency conversion and amplification is carried out, and wireless communication is carried out via an antenna according to a predetermined access procedure. Further, at the same time, the presence or absence of interference conditions in the reception band for IEEE802.11b is detected using the reception signal. Here, when wireless communication occurs using a communication link for calls on a local telephone at, for example, other scheme-compatible wireless station 30-1, or when microwave oven 40 operates, electromagnetic radiated emissions from these equipments to the band overlapping with the wireless communication using IEEE802.11b are detected as interference.
When the results of the detection of interference determine that interference exists, multimode control station 10 carries out control of switching of communication systems using control section 11, and carries out wireless communication using a wireless communication scheme conforming to the Bluetooth (registered trademark) standard using Bluetooth (registered trademark)-compatible wireless processing section 12. Further, on the other hand, detection of the presence or absence of interference in a band of IEEE802.11b is carried out in parallel using IEEE802.11b-compatible wireless processing section 13. When the results of detection of electromagnetic interference wave are that electromagnetic wave interference does not exist, multimode control station 10 switches the system for carrying out wireless communication from the system using Bluetooth (registered trademark)-compatible wireless processing section 12 to IEEE802.11b compatible wireless processing section 13, and switches to wireless communication of the IEEE802.11b standard.
By carrying out control of communication as described above using control section 11, communication between multimode control station 10 and multimode terminal station 20-1 is executed by switching the communication scheme over according to the presence or absence of interference conditions. Specifically, when there is no interference, wireless communication is carried out using a communication scheme conforming to the IEEE802.11b standard of a higher transmission speed, and when interference exists, a communication scheme conforming to the Bluetooth (registered trademark) standard where transmission speed is comparatively low but the probability of being subjected to interference is relatively low is used. As a result, it is possible to continue data transmission using wireless communication regardless of the presence or absence of interference, and it is also possible to carry out communication with good overall communication efficiency.    Patent Document 1: Japanese Patent Application Laid-open No. 2003-199160 (pages 3 to 4, FIG. 1).